The disclosure concerns a method to operate a printer or copier to print to a printing substrate, in which method toner concentrate is extracted from a toner concentrate reservoir, carrier fluid is extracted from a carrier fluid reservoir, and these are supplied to a mixer. In the mixer, the toner concentrate and carrier fluid are mixed to form a developer mixture which is subsequently applied to a developer roller in a developer station. The disclosure also concerns a corresponding printer.
In printers that operate according to the electrophoretic principle, the fluid developer mixture made of a toner concentrate and a carrier fluid is mixed together in a mixer. The developer mixture that is obtained in such a manner—which developer mixture is also designated as liquid developer—is applied to a developer roller in a developer station. Depending on the image to be printed, the developer mixture is transferred from the developer roller onto a photoconductor drum and is further transferred from this to a transfer roller. The toner is finally transferred electrophoretically from the transfer roller to the printing substrate.
The toner concentrate and the carrier fluid are supplied from corresponding reservoirs to the mixer as needed. The reservoirs must be regularly exchanged accordingly if they are completely or nearly completely empty. During this exchange, toner concentrate or carrier fluid may no longer be supplied to the mixer from the corresponding reservoir, such that a maintenance of the composition of the developer mixture (and thus a maintenance of the toner concentration) is not possible without further measures.
Therefore, intermediate stores or buffers are provided in which a predetermined quantity of toner concentrate and carrier fluid can be cached and which then is supplied to the mixer upon exchange of the corresponding reservoir. It is thus achieved that the same amount of toner concentrate or carrier fluid can be supplied as in regular operation, even upon exchange of the reservoir, such that the toner concentrate in the developer mixture remains the same.
It is a disadvantage of this method that extra modules must be provided for such intermediate storage, and thus additional scarce structural space is also required. Moreover, cost-intensive dosing valves must be provided at the intermediate stores. An additional disadvantage is that sediments often settle in intermediate containers, which can negatively affect the functionality of the printer.
From the document U.S. Pat. No. 6,229,775 B1, a printer is known in which hatches are provided via which the reservoirs can be refilled. It is hereby achieved that the reservoirs do not need to be exchanged at all.
In the document US 2013/0272733 A1, an additional printer is described in which multiple developer stations are supplied with developer mixture from an intermediate container. Depending on the printing mode, different numbers of developer stations are participating in the printing, and the fill level of the developer mixture in the mixer is preset differently depending on the operating mode.